A therapeutic catheter having at least two channels or lumens extending through it in the longitudinal direction is known from EP-A-0 527 312 (corresponds to DE 41 26 886 A1). One lumen is a flow channel to supply liquid with high pressure (for example, 75 bar), from the near or proximal end to the far or distal end of the catheter. The catheter has an open flow path on its distal end at which the liquid in the form of a sharp jet can separate parts of a body tissue in a patient and convey them into the other lumen, which serves as return channel and transports the liquid together with the separated tissue material to the proximal end of the catheter. A similar or therapeutic catheter is also known from the published Patent Application DE 42 01 992 A1. Other known therapeutic catheters, like the one known from U.S. Pat. No. 5,380,273, have one or even two expansion elements, so-called dilation balloons, on the distal end with which blood vessels in a patient can be dilated or blocked. Moreover, mechanical catheters with a rotating tool on their distal end section to remove material in vessels of a patient are known from U.S. Pat. No. 5,092,872 and the unexamined German Applications D138 01 318 A1, DE 38 28 478 A1 and DE 43 23 756 A1. PCT-WO 89/09029 also exhibits a mechanical catheter with pivotable tools on the distal catheter end.
During introduction of a catheter into a patient the physician can observe the position of the catheter on an x-ray screen. However, the tissue or condition of the tissue is not recognizable or not clearly recognizable on the x-ray screen. The physician is therefore not capable of checking the therapeutic success on-line during therapy. He receives no feedback as to whether a vascular obstruction, for example, has been sufficiently eliminated. He is forced to adopt an iterative procedure “therapy, control, therapy, and so forth” in which the physician must rely on his experience and feelings in establishing the control intervals. This procedure leads to frequent control angiographies which expose the patient to radiation and contrast agents.
To summarize, this means that, when therapeutic catheters of the aforementioned types are used combined with x-ray imaging devices, the user only receives information concerning the position of the catheter in the patient, but the actual therapeutic function is not visible.
A hydrodynamic thrombectomy catheter in which fluid is guided via a channel system to treat the patient tissue and ultrasound is guided via a separate system to the tip of the catheter for optical monitoring of catheter operation is known from EP 0 483 133 A1. The therapy channel for the fluid and the diagnosis channel for the ultrasound diagnosis are separate and independent of each other.
In catheters in which laser radiation or ultrasound is used to treat patient tissue, the function of the catheter tip in a patient tissue can be monitored simply by reflecting laser beams or ultrasound waves. Such catheters are known, for example, from the following documents: publication of the article “Laser-inducted Shockwave Lithotripsy with Microsecond Laser Pulses” in the journal Laser und Optoelektronik 20(4)/1988 by R. Engelhardt, W. Meyer, S. Thomas, P. Oehlert; published Patent Applications DE 43 22 955 A1 and DE 195 22 310 A1; Patent DE 42 40 182 C2, U.S. Pat. No. 5,104,392 and EP 0 582 766 A1. Moreover, a therapeutic catheter for treatment of patient tissue with laser light having an additional internal hollow channel to which a laser beam is transmitted for diagnostic purposes is known from DE 44 37 578 A1. Several therapeutic catheters are also known from EP 0 629 380 A1: a catheter for elimination of stenoses by laser radiation, a catheter with an expandable balloon on the distal end of the catheter to eliminate stenoses, and a catheter to treat patient vessels with ultraviolet light to prevent new formation of stenoses in blood vessels of the patient. No diagnostic possibilities are provided in these last-named catheters.